Diversity

Arvicolinae is a large subfamily of cricetid rodents that are fairly uniform in appearance but diverse in their habits. There are 151 species in this family, in 28 genera. The genera are divided among 10 tribes. (Musser and Carleton, 2005; Nowak, 1999)

Geographic Range

The subfamily Arvicolinae has a Holarctic distribution. Arvicolines are found throughout North America from Guatemala northward, throughout Eurasia, in Japan, Taiwan, southwestern China, northern India, the Middle East including Asia Minor, and in Africa to Libya. (Carleton and Musser, 1984)

Physical Description

Arvicolines are medium to large muroid rodents, ranging in head and body length from 70 mm to over 300 mm, and ranging in tail length from 5 to 295 mm. The tail is always shorter than the head and body. Arvicolines weigh anywhere from 15 grams to over 1.8 kg. They have stout bodies with small, rounded ears, blunt snouts, and short legs. The eyes are relatively large. Adult males, and sometimes females, have large sebaceous glands on the rump, hips, flanks, or tail region. Most arvicolines have cursorially adapted feet, and some have long claws for digging. Arvicoline fur is usually thick and ranges from long to short and from smooth to harsh. In some species the texture changes with the seasons, becoming shorter and thinning out in the summer. The tail is covered with fur in most species, and sometimes bears a terminal tuft. The fur on the dorsal surface of arvicolines can be various shades of brown or gray, and in some species it has a distinct red or yellow cast. The fur on the ventral surface is pale brown, white, cream, buff, yellowish, or gray. Some species have bicolored tails that are darker above than below. There are polymorphic arvicoline populations, with two or more color morphs living in the same area.

The dental formula of arvicolines is 1/1, 0/0, 0/0, 3/3 = 16. The
incisors may be orthodont, opisthodont, or proodont, and the
molars may either be
rooted or evergrowing. The molars bear a
prismatic enamel pattern. Arvicolines have relatively large
skulls. The squamosomastoid foramen is always present, and most have a stapedial foramen as well. The palatine process of the
maxillary and the
palatine are thickened dorsoventrally, in conjunction with the molars' large alveolar capsules. There are usually longitudinal furrows and ridges, as well as tiny perforations, in the bony palate. There are 13 thoracic vertebrae and six lumber vertebrae in the arvicoline vertebral column.

Arvicolines have stomachs that are either one- or two-chambered, and their large intestines and ceca are extremely complex. However, the small intestine is quite short. There is no supraorbital branch of the stapedial artery; instead, the infraorbital branch supplies blood to the orbits. Arvicolines have a diploid chromosome number between 18 and 62. (Carleton and Musser, 1984; Nowak, 1999)

Reproduction

Most arvicolines are promiscuous, with males and females both having multiple mates. In some species, a copulatory plug forms and seals the female's reproductive tract, preventing subsequent males from successfully fertilizing the female's eggs. However, a few species, such as muskrats and prairie voles, live in monogamous pairs and share the responsibility of raising young. In fact, in captivity it has been shown that prairie voles stay with their parents for more than one breeding period and help raise their younger siblings (Gruder-Adams and Getz 1985). (Carleton and Musser, 1984; Gruder-Adams and Getz, 1985; Nowak, 1999)

Many arvicolines are capable of breeding year round, and some species even give birth to litters under snow cover. Others concentrate their reproductive efforts during the warmer months and breed from spring to autumn, with a peak in breeding occurring from late spring to early summer. In some species, ovulation is not spontaneous; rather, it is induced by the act of mating. Females are polyestrus, giving birth to anywhere from 1 to 7 litters per year. They often become impregnated again as soon as they give birth, due to a postpartum estrus. However, implantation of the embryo is delayed in some species while the female is lactating. Gestation from the time the embryo implants is 16 to 30 days. Litter sizes average 3 to 7 young, but some females have as few as one and as many as 13 young in a litter. The young are relatively precocial and develop rapidly, opening their eyes at 8 to 16 days and becoming weaned and independent at 12 to 35 days. Females often breed in the year that they are born, becoming sexually mature as early as 14 days. Males mature somewhat later than females. (Carleton and Musser, 1984; Nowak, 1999)

Most female arvicolines invest little in each individual offspring, instead employing a strategy of high reproductive output. They build nests in which they rear their litters and nurse their relatively precocial young for 12 to 35 days. Often females become highly aggressive when nursing, fiercely defending their litters against intruding males. Male parental care occurs in this group, with males of some species brooding the young in the nest or retrieving them when they wander away. Also, care of youngsters by older siblings has been reported for arvicolines kept in captivity (Gruder-Adams and Getz 1985). (Gruder-Adams and Getz, 1985; Nowak, 1999)

Lifespan/Longevity

Most arvicolines only live for a few months in the wild. Captivity often extends the life span by several years. (Nowak, 1999)

Behavior

Arvicolines, as a group, display a wide range of lifestyles. Some are terrestrial, some are semi or fully aquatic, some are arborial, and some are fossorial. They are adapted for cursorial or natatorial locomotion. Most are active at any time of the day or night, some are strictly nocturnal, and a few are diurnal. They are active throughout the year. Arvicolines build nests in underground burrows, depressions in the ground, tree holes, tree branches, or under rocks or logs. Some maintain complex tunnel systems underground, through the grass, or under the snow. Underground tunnel systems often have multiple entrances and consist of a nest chamber and adjacent chambers for food storage and defecation.

Arvicolines range in social habits from solitary, aggressive, and territorial to gregarious and colonial. In some species, population densities become extremely high in certain years, prompting mass migrations. These population increases are often cyclical in nature, occuring at regular intervals. (Carleton and Musser, 1984; Nowak, 1999)

Communication and Perception

Arvicolines are able to perceive tactile, visual, auditory, and chemical signals. Chemical signals are especially important for communication. Males, and sometimes females, mark their territories with secretions from their sebaceous flank glands. Also, some arvicolines are highly vocal and make a variety of chirping and chattering noises when disturbed or when engaged in a conflict with a conspecific. (Nowak, 1999)

Food Habits

Arvicolines are primarily herbivorous, though some species are omnivorous. They consume leaves, grasses, forbs, roots, bulbs, bark, twigs, stems, pine needles, berries, nuts, seeds, lichen, fungi, insects, crayfish, mussels, and small fish. Some species cache food in their nests or burrows for use during times of shortage. (Carleton and Musser, 1984; Nowak, 1999)

Predation

Hawks, owls, snakes, and small mammalian carnivores are the main predators of arvicolines. Arvicolines can be quite vicious, gnashing their teeth and biting when threatened. Also, their neutral-colored fur probably keeps them somewhat camouflaged. (Carleton and Musser, 1984; Nowak, 1999)

Ecosystem Roles

Arvicolines are primary and secondary consumers, and they provide a staple food source for many other species. The fossorial species turn over earth when they dig, and therefore may help to aerate the soil. Arvicolines are important for seed dispersal, and they impact forest regeneration by preying on tree seedlings (Manson et al. 2001). Because of their important role in forest dynamics, some are considered keystone species. Finally, because of their high reproductive output and cyclical boom and bust cycles in population numbers, the population dynamics of arvicolines often influences heavily the population dynamics of predators such as snowy owls and Canada lynx, and plant community composition through their grazing activity. (Manson, et al., 2001; Nowak, 1999)

Other Comments

The earliest undisputed arvicoline fossils are from the early Pliocene of northwest Asia, Europe, and North America. It is thought that arvicolines spread into southern Asia in the late Pliocene. (Musser and Carleton, 2005)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Allison Poor (author), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

Neotropical

living in the southern part of the New World. In other words, Central and South America.

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

bog

a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.

carnivore

an animal that mainly eats meat

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

chemical

uses smells or other chemicals to communicate

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

cooperative breeder

helpers provide assistance in raising young that are not their own

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

delayed implantation

in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months.

diurnal

active during the day, 2. lasting for one day.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

folivore

an animal that mainly eats leaves.

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

frugivore

an animal that mainly eats fruit

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

holarctic

a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.

Found in northern North America and northern Europe or Asia.

induced ovulation

ovulation is stimulated by the act of copulation (does not occur spontaneously)

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

keystone species

a species whose presence or absence strongly affects populations of other species in that area such that the extirpation of the keystone species in an area will result in the ultimate extirpation of many more species in that area (Example: sea otter).

marsh

marshes are wetland areas often dominated by grasses and reeds.

migratory

makes seasonal movements between breeding and wintering grounds

molluscivore

eats mollusks, members of Phylum Mollusca

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

mycophage

an animal that mainly eats fungus

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

piscivore

an animal that mainly eats fish

polar

the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

polymorphic

"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic.
Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

soil aeration

digs and breaks up soil so air and water can get in

solitary

lives alone

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

taiga

Coniferous or boreal forest, located in a band across northern North America, Europe, and Asia. This terrestrial biome also occurs at high elevations. Long, cold winters and short, wet summers. Few species of trees are present; these are primarily conifers that grow in dense stands with little undergrowth. Some deciduous trees also may be present.

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

tundra

A terrestrial biome with low, shrubby or mat-like vegetation found at extremely high latitudes or elevations, near the limit of plant growth. Soils usually subject to permafrost. Plant diversity is typically low and the growing season is short.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

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The Animal Diversity Web is an educational resource written largely by and for college students. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.

This material is based upon work supported by the
National Science Foundation
Grants DRL 0089283, DRL 0628151, DUE 0633095, DRL 0918590, and DUE 1122742. Additional support has come from the Marisla Foundation, UM College of Literature, Science, and the Arts, Museum of Zoology, and Information and Technology Services.